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removed, and the surfaces of the specimen left Example 10 A specimen ofcommercially pure magnesium taken from a rolled sheet of that metal wascleaned and left bright and shiny in 3 minutes by treatment at aboutroom temperature in an aqueous solution containing per cent sulfuricacid, 0.5 per cent malic acid, and 0.5 per cent oxalic acid.

These examples are given to indicate the compositions and methods ofoperating the solutions used in the practice of my invention, and itwill be understood that variations in its practice are possible withinthe scope of the appended claims.

I claim:

1. The method of cleaning magnesium articles which comprises subjectingsaid articles to the action of an aqueous solution containing from about1 to about per cent sulfuric acid and a total of from about'0.5 to aboutper cent of at least one aliphatic polybasic acid selected from thegroup consisting of oxalic, malic, citric, and tartaric acids. 7

2. The method of cleaning magnesium articles which comprises subjectingsaid articles to the action of an aqueous solution containing from about2 to about 6 per cent sulfuric acid, and a total of from about 3 toabout 5 per cent of at least one aliphatic polybasic acid selected fromtartaric acids.

3. The method of treating wrought magnesium articles in order to removelubricants and other impurities therefrom and to produce a bright shinysurface thereupon, which method comprises subjecting said articles tothe action of an v aqueous solution containing from about 1' to about 10per cent sulfuric acid and a total of from about 0.5 to about 15 percent of at least one aliphatic polybasic acid selected from the groupconsisting of oxalic, malic, citric, and tartaric acids.

4. The method of cleaning magnesium articles and producing bright shinysurfaces thereupon which comprises subjecting said articles to theaction of an aqueous solution containing from about 1 to about 10 percent sulfuric acid and 0.5 to about 15 per cent citric acid. I 5. Themethod of cleaning magnesium articles and producing bright shinysurfaces thereupon which comprises subjecting said articles to theaction of an aqueous solution containing from about 1 to about 10 percent sulfuric acid and 0.5 to about 15 per cent tartaric acid.

6. The method of cleaning magnesium articles and producing bright shinysurfaces thereupon which comprises subjecting said articles to theaction of an aqueous solution containing from about 1 to about 10 percent sulfuric acid and 0.5 to about 15 per cent oxalic acid.

MIKE A. MILLER.

the group consisting of oxalic, malic, citric, and Q June 23,1942. A. J.MUMMERf 2,287,051

PAcKI'Ne RING Filed Jan. 6, 1940 INVENTOH; HBO-6N1]. MUMMEHT HTTO NEY

